The present disclosure describes systems and techniques relating to calibration of I/Q mismatch in wireless communication systems.
An I/Q mismatch (also referred to as an I/Q imbalance in some instances) occurs due to mismatches between the in-phase (I) and quadrature (Q) signal paths of a transceiver such as a direct conversion transceiver. The transceiver uses a local oscillator (LO) to generate a sinewave. A copy of the sinewave is phase shifted by 90 degrees to produce a quadrature sinusoidal component. The direct LO output is mixed with the original signal, which produces the I signal, whereas the shifted LO output is mixed with the original signal, which produces the Q signal. When mismatches exist between the gain and/or phase of the two sinusoidal signals, the quadrature signals will be corrupted and cause signal demodulation error. In some instances, calibration of I/Q mismatch is performed to compensate, offset, or otherwise control the IQ imbalance so as to reduce or eliminate signal degradations caused by the I/Q mismatch.